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Highly grain-oriented lead metaniobate (PbNb2O6; PN) ceramics were prepared by a layered manufacturing (LM) process. This process has enabled us to obtain a net-shaped piezoelectric ceramic component with grain orientation of f∼89%, and improvement in electromechanical properties. The LM feedstock (filament) includes equiaxed (matrix; 90 vol%) and anisometric PN templates (10 vol%), both dispersed uniformly in a thermoplastic binder. The needle-like PN templates were synthesized by molten salt synthesis technique, while the equiaxed PN powder was prepared by conventional ceramic processing methods. The processing conditions were studied and optimized to obtain orthorhombic phase fine powder and anisometric templates. Samples were obtained through layer-by-layer deposition of the filament through a small diameter (500 μm) nozzle. After binder removal, the PN samples were sintered in a temperature range of 1150°–1300°C for 1 h. SEM observation revealed strong grain orientation perpendicular to the deposition direction. Relative permittivity at the Curie point ( Tc: 560°C) was 18 100 and 14 600 for the LM and random polycrystalline samples, respectively. Improved properties in piezoelectric figure of merit by 71%, d33 by 23%, and g33 by 31% were observed in the grain-oriented samples. Remnant polarization also showed about 80% improvement, increasing from 4.5 to 8.1 μC/cm2 for the grain-oriented LM samples. [ABSTRACT FROM AUTHOR]

A method for synthesis of high aspect ratio platelet seeds by growth of SrTiO3 on Sr3Ti2O7 core particles is reported. The aim of this study was to identify and control the morphology and size of SrTiO3 particles via molten salt synthesis. Platelet and tabular morphologies with rectangular faces were obtained using rutile and anatase, respectively. Platelet SrTiO3 particles with an edge length of 10–40 μm and a thickness of 1–4 μm were obtained. High aspect ratios (edge length to thickness) of 7–10 were measured for platelet particles as opposed to lower aspect ratios of 2–4 for tabular particles. Highly anisotropic platelets are suitable template candidates to achieve textured ceramics. [ABSTRACT FROM AUTHOR]

In the last 25 years, piezoelectric ceramicpolymer composites have been conceptualized, prototyped, fabricated, and implemented in an array of applications encompassing medical imaging and military missions, among others. A detailed snapshot of the materials used, and a detailed account of the major innovative methods developed in making various piezoelectric ceramic-polymer composites are presented. The salient aspects of processing of such composites are summarized, and structure-processing-property relations are described using connectivity as the unifying central concept. Computer-aided design (CAD)-based fabrication methods, which result in composites whose structural complexity surpass that of composites obtained with traditional methods, are described to introduce the reader to novel concepts in processing of piezocomposites. A brief survey of some recent advances made in modeling of (0-3), (1-3), and (2-2) composites also is provided. [ABSTRACT FROM AUTHOR]

Grain-oriented lead-metaniobate (PbNb 2 O 6 ; PN) components have been fabricated by fused deposition of ceramics (FDC) process using templated grain growth technique. Needle-shaped PN seeds were synthesized for the templates by molten salt method. About 5 wt% seed was mixed with fine equiaxed matrix PN powder and compounded with a thermoplastic binder to obtain 52 vol% solids loading. Filaments extruded from the compounded materials were fed into FDC liquefier with a fine nozzle to prototype PN components through layer-by-layer deposition. SEM observations in the components showed that the seeds were aligned parallel to the deposition direction, surviving without major damage. By sintering at 1300 °C, a highly oriented microstructure with orthorhombic phase was successfully obtained. [ABSTRACT FROM AUTHOR]

Three-dimensional photonic bandgap (PBG) structures using alumina (Al2O3) as the high permittivity material were modeled and then the structures were fabricated by Fused Deposition of Multi-materials (FDMM) technology. A finite element method and a real-time electromagnetic wave propagation software were used to simulate and design the layered PBG structures for applications in the microwave frequency range. The modeling predicted a 3-D photonic bandgap in the 16.5–23.5 GHz range. FDMM provides a computer-controlled process to generate 3-D structures, allowing high fabrication flexibility and efficiency. Electromagnetic measurements displayed the presence of a bandgap between 17.1–23.3 GHz, showing a good agreement with the predicted values. These PBG structures are potential candidates for applications in advanced communication systems. [ABSTRACT FROM AUTHOR]

Characterizes Blackgas-Nextel 312 composites with and without filler materials. Incorporation of SiC as inactive filler and Ti and TiB[sub 2] as active fillers into the Blackglas resin; Obtaining of higher moduli for filled composites.